Quantitative evaluation of evaporation rate during spin-coating of polymer blend films: Control of film structure through defined-atmosphere solvent-casting.

Abstract

Thin films of polymer mixtures made by spin-coating can phase separate in two ways: by forming lateral domains, or by separating into distinct layers. The latter situation (self-stratification or vertical phase separation) could be advantageous in a number of practical applications, such as polymer optoelectronics. We demonstrate that, by controlling the evaporation rate during the spin-coating process, we can obtain either self-stratification or lateral phase separation in the same system, and we relate this to a previously hypothesised mechanism for phase separation during spin-coating in thin films, according to which a transient wetting layer breaks up due to a Marangoni-type instability driven by a concentration gradient of solvent within the drying film. Our results show that rapid evaporation leads to a laterally phase-separated structure, while reducing the evaporation rate suppresses the interfacial instability and leads to a self-stratified final film.

DOI: 10.1140/epje/i2010-10670-7

Cite this paper

@article{MokarianTabari2010QuantitativeEO, title={Quantitative evaluation of evaporation rate during spin-coating of polymer blend films: Control of film structure through defined-atmosphere solvent-casting.}, author={Parvaneh Mokarian-Tabari and Mark Geoghegan and Jonathan Howse and Sasha Y Heriot and Rodger L. Thompson and Roy A. L. Jones}, journal={The European physical journal. E, Soft matter}, year={2010}, volume={33 4}, pages={283-9} }